I was looking at pictures of N130Q, and the obvious question is how much room is required to take off and land when on water? Assuming the plane is empty, it probably wouldn't be that much right? What about loaded?

Yep. There's an article in the July 1998 Airways about it that talks about the plane the OP is asking about. The USAAF originally ordered 150 sets of Edo 78-29 400 floats for C-47's. Only 30 were ever manufactured and not all were actually installed. C-47s with floats were designated C-47C's.

N130Q was originally a C-53D Skytrooper delivered in October '43, acquired by Eastern in November of '45. Modified to DC-3 standards and stayed in service with Eastern until 1952. Sorry I don't have any info on landing/takeoff, but I do love old floatplanes.